Transport protocol not being obeyed

[mloehnig]

Your environment.

• Version: 2.1.7
• Browser: Chrome Version 89.0.4389.114 (Official Build) (64-bit)
• Coturn: debian/4.5.2-3
• Firewall: UDP not allowed

What did you do?

Using the latest version of coturn implementation with the no-udp flag specified and a strict firewall preventing UDP traffic one would observe that the ice candidate gathering takes 5 seconds. After some investigation I found that the transport=tcp flag was not being obeyed within the gatherCandidatesSrflx function.

What did you expect?

When transport=tcp is specified only TCP connections are established to the stun/turn server.

What happened?

When transport=tcp is specified there is an attempt to connect to the stun/turn server using UDP and in my particular case caused ICE gathering to take 5 seconds to complete.

Potential solution

https://github.com/pion/ice/pull/366